I will try my best to describe whats going on here in this video.
Back-leg Front Kick: start with the heels together at a 90 degree angle or an L shape. Weight distrobution 50-50 on each leg. Open the front foot like kicking a soccer ball, and transition 100% weight onto this foot. Raise the knee from the back leg straight up. This is important. Then extend the foot outward, toe pointed in a stabbing the upper stomach sort of kick. Snap the kick and bring the kick back to the knee raised position. Practice being sturdy on the plant leg, the kick power comes from the leg on the ground.
Back-let Round House Kick: Start the same as the front kick. All kicks start with the knee being raised straight up in a knee strike before the kick is snapped. After the knee is raised rotate the body on the back hip so the front leg is turned and the knee is pointed to the target. Extend the leg outward, contact is to made with the top of the foot. Snap the kick and bring the leg back to the knee up and rotated position (chambered leg). Then set it down. Be sturdy on the plant leg. The power comes from the plant foot.
I thought I would be able to talk about the hand movements here as well but its just too technical to describe